Method and apparatus for dressing grinding wheels



D 26,1944. E. WILDHABER Em Y 2,366 1 METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS 7 Filed Nov. 26, 1943 7 Sheets-Sheet 1 Minimum Dec. 26, 1944. W|LDHABER 2,366,139

METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS Filed Nov. 26, 1943 7 Sheets-Sheet 2 3nnentors D8526, 1944. w LDHA R ET AL 2,366,139

METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS Filed Nov. 26, 1943 '7 Sheets-Sheet 3 3nventors Dec. 26, 1944. E. WILDHABER ET AL I ,3

METHOD AND APPARATUS FOR DRESSING GRINDING WHEE LS Filed NOV. 26, 1943 7 Sheets-Sheet 4 i J .55/ 1;, v

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METHOD AND APPARATUS FOR DRESSING GRINDING WHEELS Filed Nov. 26, 1943 7 Sheets-Sheet 5 M i-Whom;

Dec. 2-6, 1944. E. WILDHABER ET AL 2,366,139 METHOD ANDWAPPARATUS FOR DRESSING GRINDING WHEELS Filed Nov. 26, 1943' 7 Sheets-Sheet 6 Mormons m7 wmm 5 HW Q msfi 7 m 52H. E07

26, 1944. E. WILDHABER arm. 9

METHOD AND APIARATUS FOR DRESSING CiRINDING WHEELS Filed Nov. 26, 1943 '7 Sheets-Sheet 7 FIG 19 ZmventorS 512N657 MAM/455. 2 B men/a2 STEM/ART AQTHUZ FUM/A Wammeg Patented Dec. 26, 1944 NIETHOD AND APPARATUS FOR DRESSING GRINDING WHEELS Ernest Wildhaber and Arthur L. Stewart, Brighton, and Arthur Fumia, Rochester, N. Y.,

signors to Gleason Works, Rochester, N. Y., a corporation of New York Application November 26, 1943, Serial No. 511,802

ly employed. I he problem of dressing the tip 20 Claims. The present invention relates to methods and to apparatus for dressing grindingwheels and particularly to a method and apparatus for dressing cup-shaped grinding wheels such as are employed in the grinding of spiral bevel and hypoid gears without generating roll.

Indressing a gear-grinding wheel, it is customary to dress the tip and both sides of the wheel, and the practice is to use separate side and tip-dressing tools for this purpose. The side and tip-dressing tools are ordinarily connected together to perform and complete their respective operations simultaneously. As a result, with the dressing mechanisms employed until quite recently, the tip of a gear-grinding wheel has been dressed to a much finer finish than the sides of the wheel, because the width of the tip of a gear-grinding wheel is always less than the height of the sides of the wheel, and if the sidedressing tools are required to complete their operations in the same period of time as the tipdressing tool, the tip-dressing tool will naturally move slower and therefore dress a finer finish on the wheel.

This was of no consequence in the automotive field for the bottoms of the tooth spaces of automotive gears and the fillets, which join the tooth space bottoms with the sides of the tooth spaces, are not ground. In the airplane field, however, the tooth space bottoms and the fillets have to be ground, in addition to the sides of the teeth,

in order to eliminate all surface cracks. Surface cracks are always points of incipient breakage, particularly under the heavy loads which airplane gears have to carry. It has been discovered that if the tips and rounds of the grinding wheel of a cup-shaped gear-grinding wheel simultaneously with the sides of such a wheel with a finish no finer than the finish of the sides is a different and much more dimcult problem than that of so dressing an annular wheel.

An annular grinding wheel grinds thelengthwise tooth shape on a longitudinally curved tooth gear by simple rotation of the wheel on its axis. The axis of the wheel is perpendicular to the plane of operation. Moreover, the tip of the wheel usually lies in that plane. As a result, the

side-dressers employed in dressing an annular 1 grinding wheel can be positioned at one point around the periphery of the wheel and the tipdresser at anotherpoint, and the side and tipdressers can be operated at different rates of speed without possibility of interference with one tooth gear.

therefore, to be inclined to its plane of operation,

are dressed too fine, the bottoms and fillets of the tooth spaces of the gears are likely to be burned in the course of grinding. This is damgerous because a burned surface is a surface full of cracks and ripe for breakage under load.

Recently, a dressing mechanism has been devised for dressing rotary annular grinding wheels which will permit of dressing the tips of such wheels simultaneously with the sides of the wheels but with the tip-dresser travelling at a rate faster than the rate of movement of the side-dressers so as to dress the tip of the wheel to a finish another.

A cup-shaped gear grinding wheel, however, has tobe oscillated about an axis separate from its own axis of rotation in order to grind the lengthwise tooth shape on a longitudinally curved The axis of a cupped wheel has,

and to avoid excessive and impractical complications in the dressing mechanismand in its adjustment, the side and tip-dressing tools for dressing a cupped wheel have to be arranged to operate at, the same point around-,the periphery of the wheel. In this position, the side and tipdressing tools can all be operated simultaneously at the same speeds and will clear one another, but they cannot be operated at diiferent speeds without interference. The method, used in the dressing of annular wheels, for obtaining a sumciently coarse finish on the tips and rounds of the wheel while getting the required fineness of finish on the sides, cannot be applied, therefore to the dressing of cup-shaped wheels.

Beyond this, another problem has arisen in connection with the dressing of cup-shaped geargrinding wheels. Such wheels ordinarily, have side surfaces of straight profile. for more accurate gears has increased, however, it has become more and more desirable to dress all bevel and hypoid gear-grinding wheels with side surfaces of curved profile to overcome certain tooth bearing conditions encountered on spiral bevel and hypoid gears that have been ground. In the dressing mechanism employed for dressing annular grinding wheels, control of the profile shape can be obtained very readily by adjustment-of the position of the axis of swing of the dressing tool up or down to change the As the demand "v point around the periphery of the wheel at which a cupped wheel, the wheel is journaled in a quill which is oscillated back and forth, as the wheel rotates, to grind the tooth sides of a gear to the desired lengthwise curvature; the dressing mechanism is mounted on the quill housing at one side of and beyond the working path of the wheel; and when it is desired to dress the wheel, the oscillating movement of the quill is stopped and the quill is swung beyond its normal working path to bring the wheel into operative relation with the dressing mechanism. Even though thedressing mechanism has thus been disposed out of the way of the working path of the wheel, on some jobs there is not sufiicient clearance between the dressing mechanism and the work support during grinding. This has definitely limited the capacity of spiral bevel and hypoid gear grinders of the non-generating type.

One object of the present invention is to provide a dressing mechanism, particularly for dressing cup-shaped gear grinding wheels, in which the tip of the wheel may be dressed in the same operation as the dressing of the sides of the wheel but with a finish coarse enough to avoid burning of any workpiece ground by'thewheel.

Another object of the invention is to provide a dressing mechanism for dressing the sides and tip of a cup-shaped grinding wheel and the rounds, which join the sides with the tip, with which the tip and rounds may be dressed to have approximately the same finish as the sides so that the wheel can be used to grind the sides, bottoms, and fillets'of the tooth spaces of a gear to substantially uniform tooth surface finish.

' A further object of the invention is to dress the sides and tip of a cup-shaped grinding wheel so that the wheel can grind gears faster without danger of burning than they can be ground by In the conven- .the dressing tool contacts the wheel. This soluvide a dressing mechanism of the character described which is fiuid-pressure operated and inwhich the movements of the side and tip-dressers to and from operative position as Well as the operation of these dressers when in operative position can be controlled by a single controlvalve. Another object of the invention is to provide a dressing mechanism which can be adjusted readily for dressing wheels of various diameters, heights, pressure angles, and profile shapes.

Other objects of the invention will beapparent hereinafter from this specification and from the recital of the appended claims.

In the'drawings:

Figdd is a fragmentary front elevation of a conventional type of spiral bevel and hypoid gear grinding machine, showing, the cupped grinding wheel of the machine swung up t dressing position and showing a dressing mechanism constructed according toone embodiment of this invention mounted on the machine and in operative engagement with thdgrinding wheel;

Fig. 2 is a transverse sectional view through the dressing mechanism and-wheeltaken in the radial plane of the wheel in which the dressing tools engage the wheel at the mean points" of the strokes of the tools;

Fig. 3 is a part elevational and part sectional view, looking at the dressing mechanism from the right hand side of Fig.2 but with the side-dressing tool and its actuating parts removed;

Fig. 4 is a sectional view taken on the line 4.-4 of Fig. 3;

Fig. 5 is a sectional view'taken on of Fig. 3;

Fig. 6 is a sectional view on Fi 1;

Fig. 7 is a section on the line l--! of Fig. 1;

the line 55 the line 64 of Fig. 8 is a detail view showing the eccentric for adjusting the radial position of the tip-dresser;

Fig. 9 is a transverse sectional view of thetipdresser;

Fig. 10 is a sectional view through one of the side-dressers;

Fig. 11 is a perspective view of one of the adjustable blocks for controlling the profile shapes dressed on the wheel;

Fig. 12 is a diagrammatic view, illustrating the operation of the outside-dresser;

Fig. 13 is a diagrammatic view showing the path of the ball-follower across the control block in the operation of the outside-dresser;

wheels dressed according to conventional practice. 1

Another object of the invention is to provide a dressing mechanism which may be used to dress the side of a grinding wheel to either a straight or a curved profile shape.

A further object of the invention is to provide a dressing mechanism which may be used to dress a curved profile on a side of a grinding wheel in which the radius of curvature of the profile dressed and its convexity or concavity may be controlled by adjustment of a simple and single control member or cam:

A further object of the invention is to provide a dressing mechanism having side and tip-dressers which is so mounted and operated as to swing out of operative position upon completion of a dressing operation, so as to permit grinding any gear within the capacity of the machine, on which the dressing mechanism is used, without danger of interference of the dressing mechanism with the work or with the work support.

Still another object of the invention is to pro- Fig. 14 is a diagrammatic view similar to Fig. 12 illustrating the-operation of the inside dresser;

Fig. 15 is a diagrammatic view similarto Fig. 13

. showing the path of movement of the. ball-fol- Fig. 19 is a section on the line l9-l9 of Fig. l8.

In the preferred embodiment of the present invention, the side and end-dressing tools are mounted on three separate, swinging arms that in each dressing operation are swung first forward and then back, and each of which can be moved axially simultaneously with its swing in order to vary the. shapes of the surfaces dressed on the wheel. This follows conventional practice.

The tip-dresser is preferably made identical with the tip-dresser disclosed in the pending application of Ernest Wildhaber, Serial No. 473,067, filed January 21, 1943. It is mounted so thatthe tip-dressing tool may swing across the tip of the wheel in a generally elliptical path and it is provided with a control cam that can be adjusted ,tomove the dressing tool axially as it swings,

whereby to modify the elliptical path and produce a flattened surface onthe tip of the wheel with rounds joining the tip with the sides of the wheel.

The side-dressers are in some respects quite in a block which is mounted for rectilinear adjustment in two .directions at right angles to one another. One adjustment is for positioning the tip-dresser in accordance with the height of the wheel to be dressed. The other adjustment is for positioning the tip-dresser radially of the wheel independently of the radial adjustment of the side-dressers. The block carrying the tip dresser is pivotally mounted on the same slide that carries the side-dressers. The pivotal sup port of the tip-dresser block is for moving the V tip-dresser into and out of engagement with the similar to prior types of side-dressers, particularly to those employed on generating types of gear grinders for dressing rotary annular wheels.

They difier from conventional types of sidedressers, however, in the means employed for controlling the axial movements of the dressing tools. Heretofore, cams have been employed for this purpose, and a different cam has been required whenever a different profile shape is to be dressed. In the side-dressers used in the preferred embodiment of the present invention, control members are used which have plane control surfaces and which are mounted to be adjustable angularly about axes offset from and at right angles to the axes of swing of the two sidedressers. Each side-dresser arm carries a ball follower that rides over the plane surface of its control member as the dresser arm swings back and forth. When the control member is in zero tip of the grinding wheel, as will be described further hereinafter. Theslide, which supports both the side and end-dressers, is carried by an arm which is pivotally mounted to swing the I whole dressing mechanism, including side and position, its plan surface is at right angles to r the axis of swing of the side-dresser arm and no axial movement is imparted to the dresser. Hence a straight profile is dressed on the side of the wheel. When the control member is adjusted angular-1y, its plane control surface is at an acute or an obtuse angle to the axis of swingof thedresser. In such case, the dresser arm will be moved axially as it swings, and the tool will dress either a convex or a concave surface on the wheel, depending on whether the dresser is the inside or outside dresser and depending on whether the control member is adjusted to an acute or an obtuse angular position. The radius of curvature of the profile dressed depends on the angularity of the position'of the control member.

Both side and tip-dressers are fluid-pressure operated. The side-dressers are actuated through movement ofa-piston which is provided on opposite sides with racks that mesh with spur pinions'that are secured to the side-dresser arms. The tip-dresser is actuated through movement of a piston which is provided with a rack that meshes with a spur pinion'which is connected to end-dressers, into and out of operative position.

Both the pivotal movement of the tip-dresser and the pivotal movement of the slide are efl'ected by fluid-pressure operated pistons,

The operation of the several fluid-pressure operated pistons is controlled by a single valve. This valve controls directly the movements of the piston, which moves' the dressing mechanism into and out of operative position, and of the pistons, which operate, the side and tip-dressers, and it controls through a shuttle valve the piston which -'moves the tip-dresser into and out of engage- -ment with the wheel. Separate throttle valves govern the rates of movement of the side and tipdresser pistons in opposite directions:

When it is desired to dress the grinding wheel,

the control valve is first moved part-way in one I direction to cause the whole dressing mechanism to be swung into operative dressing tool may swing acrossthe tip of the wheel at a ratesufllciently fast to dress the tip and rounds on the wheels to a finish of desired fineness but still sufficiently coarse as not to burn a gear. Since the side-dresser piston is operatively connected with the tip-dresser piston, its

the tip-dresser arm. ,The, side and tip-dresser pistons are connectedtogether, asheretofore, so that they operate at the same speed, and a different ratio of gearing is employed between the side-dresser piston and the side-dresser arms from that employedbetween the tip-dresser piston and ,the tip-dresser arm so that the strokes of side and tip-dressing tools can be completed simultaneously.

The side-dressers, their control members, and

their operating pistonare mounted in a-block ,which' is 'angularly adjustable to permit positioning the dressers in accordance with the pressure angles to be dressed onthe inside and outside surfaces of the wheel. This block is mounted on a slide that is adjustablerectilinearly to position the side-dressers radiallyin accordance with the diameter of the wheel. ,The tip-dresser, its dontrol cam, and its operating piston are mounted movement is also throttled, but the side-dressers will. travel across the sides of the wheel faster than the tip-dressing tool travels across the tip and thus will. dress coarser surfaces on the sides of the wheel to provide rough-dressed surfaces.

The control valve is then moved backone step,

causing the side-dressers to be traversed back across the sides of the wheel at a relatively slow rate under control of the other throttle valve so that they finish-dress the sides of the wheel. Simultaneously, the shuttle valve above referred to is shifted, causing the tip-dressing tool to be 7 disengaged from the wheel so that during its retumstroke, it will not dress the wheel atall but willleavethe tip and rounds of the wheel with the flnishproduced'on its forward stroke. Usually the two throttle valves are adjusted so that the rates of movement of the side and tip-dressers, respectively, under control of these valves, is substantially the same so-that the same finish will be dressed on the sides andtip of the wheel; The dressing operation is now completed. Then the operator moves the control valve back the second step to its original position, causingthe bracket, which carries the dressing mechanism, to beswung away from the wheel, to move aide 4- s i 2,366,139 v w provide a cylinder 53 (Figs. 3 and6) in which. is

and tip-dressers out of operative position so that they may completely clear the work when the wheel is in use.

Reference will now be had to the drawingsfor amore detailed description of the invention. denotes the upright or column of the grinding machine, which may be of the general type shown in Bullock et al. Patent No. 2,099,674, granted November. 23, 1937. 2| is the oscillatable quill which is journaled in this column, and W is the grinding wheel. The wheel is mounted on a spindle (not shown) that is journaled in the quill 2| with its axis at an angle to the axis of the quill. As already stated, as the grinding wheel rotates on its axis, the quill is oscillated to effect the grinding operation; and when-the grinding wheel is to be dressed, the quillv is swung beyond its normal working path far enough to bring the wheel into operative relation with the dressing mechanism. This latter position is shown in Fig. '1

Secured to the column 20, as by means of bolts 28 and 29 (Figs. 3 and 4), are two brackets l5 and I6. Pivotally mounted on these brackets is .the support 22 (Figs. 2 and 3). This support is fastened by means of a pin 23 to a shaft 24 which is joumaled on anti-friction bearings 25 and 26, respectively, in the brackets l5 and I6 and which serves as the pivot for the support 22.

The support 22 is adapted to be swung about .the axis of shaft 24 by fluid-pressure. For this purpose, the shaft 24 is keyed at its lower end to a rotary piston which is mounted to oscillate in a cylinder 3|. Also mounted within the cylinder 3| is a partition member 34 which'serves to limit the movements of the piston in the cylinder. The cylinder is secured. to the bracket I6 by screws 32 and 33 and the partition member34 is secured to the side wall of thecylinder by screws 35 and the dowel pin 36.

. Movement of the support 22 is limited in one direction by a stop 38 which is threaded into the bracket l5 and which is adapted'to engage with a hardened stud or pin 39 that is carried by the support 22. Movement of the support 22 in the opposite direction is limited by a stop 46 which engages with a lug 4| that is integral with the support. The stop 38 serves to limit the swing of the dressing mechanism'to operative position and the stop 40 serves to limit the swing of the dressing mechanism to inoperative position. A springpressed plunger 42, which is housed in the wall of cylinder 3| and which has a beveled head 43, serves to engage behind the lug 4| to resiliently hold thesupport 22 in inoperative position.

The support 22 is provided with a guide portion and on this there is mounted for rectilinear adjustment a slide 46-. This slide is adjusted on the support by means of a screw shaft 41 which is joumaled in the support and which threads intoa nut 48 (Fig. 5) that is secured to the slide. A scale 16 (Fig. 1), which is secured to support .22 and a pointer .18, that issecured to slide 46,

and reads against the scale, and a graduated dial 44, which is secured to the shaft 41,'permit of adjusting the 'slide preciselyon the support. The

, slide may be secured in any adjusted position by bolt I6 (Figs. 1 and 3) which passesthrough elongated slot 19 formed in slide 46 and which threads into the support 22.

The slide 46 is formed with two forwardly projectingarms in whichis journaled on anti-fric- "tion bearings 46 and50 the shaft 5|. Secured to this-shaft is a block 52"(Figs. 3 and 5) which is adapted to be rocked about the axis of the shaft ii. For this purpose, the block 52 is bpredto 7 mounted a reciprocable piston 54. This piston is formed .with a portion 56 which projects through one end wall 6| of the cylinder 53 and which engages a hardened stop button 51 that is mounted in the slide 46. The piston is formed at its other end with a portion 56 which engages a hardened stop: button 59 that is mounted in theother end wall 60 of the cylinder 53. V The movements of thepiston 54 are controlled 'by-a shuttle valve 62 which is mounted to reciprocate in a sleeve64. This sleeve is secured in a-hole bored in'block 52 parallel to cylinder bore. 53. The valve 62 is constantly urgedin one direction by a. coilspring 65 that. is mounted in a recess in the .valve and that seats at one end I against the end-plate 6|. The sleeve 64' is provided with three series of radial ports that are denoted at 66, 61, and 68, respectively. The pressure fluid is admitted to the valve 62 through a pressure line 10 and is exhausted from the valve through an exhaust line H. The, valve is shift-' haust through ports 6'! and 68 and line H.

' a nut 8| that threads into the block 52.

the duct l5 is on supply, however, the block 52 l in the bracket 85 and which threads into a. nut- The block 52 is constantly urged in one direction about the axis of shaft 5| by a coil spring (Fig. 7) vwhich seatsfat one end in a recess formed in the slide 46 and at its opposite end in When is rocked about the axis of shaft 5| against the resistance of the spring 80. A stop button 82 (Fig. 7) whichis carried by the block 52 and which engages with a stop button .83 that is carried by I the slide 46, serves to limit the rocking movement of block 52 under fluid-pressure. v

Mounted on the block 52 for rectilinear adjustment thereon is a right angle shaped bracket 65 (Figs. 3-and 5). the block 52 by' T-bolts 86 and 81 whose heads engage in a T-slot 88 formed in the face of the. block'52. The T-bolt 81 is mounted in an eccentric sleeve 89 which is rotatable in an elon-. gated slot 9| (Fig. 8) formed in the bracket 65.

Rotation of the eccentric 89 permits fine adjustment of the bracket on the block 52. This serves for positioning the radial position of the end-dresser. independently of the radial adjustment ofthe' side-dressers, as will be described later. This is an important feature of the mechanism since it enables the tip-dressing tool to'be adjusted so that the rounds dressed thereby may blend with the sides of the wheel without any to the direction of adjustment of'the bracket itself is the housing 90 which supports the tipdresserand its operating parts. This housing may be adjusted on the bracket 65 by rotation of the screw shaft I01 (Fig. 5) which is journaled (not shown) that: is securedin the housing. This adjustment'canbe made precisely through use shaft I01 and through use of a pointer H6 of the' graduated dial I66 which is secured to (Fig. 3) which is secured to bracket"85 and which reads against a scale H9 that is fastened The bracket 85 is secured to to housing 99. The housing is secured in any adjusted position by bolts I99 which pass through elongated slots in bracket 95 and which thread into housing 99.

As already stated, the tip-dresser shown is of the construction disclosed in the pending application of Ernest Wildhaber, Serial No. 473,067,

field January 21, 1943. The tip-dressing tool 92 is clamped in an arm 93 (Fig. 9) that is mounted on a sleeve 94 to be angularly adjustable thereon but to be clamped thereto after adjustment. The sleeve 94 is mounted on a shaft 99 and i keyed thereto. It is formed with clutch teeth on its inner end to engage with clutch teeth formed on the opposing end face of a sleeve 95. The sleeve 95 is also mounted on shaft 99. The tip-dresser housing 99 is so mounted on the bracket 95 that the axis of shaft 99 is inclined 'at other than with spur gear segments I29 and I39, respectively,

right angles to the tip-plane of the grinding wheel, so that the dressing tool may dress an elliptical shape as the tool swings across the tip of the wheel.

The sleeve 95 is adapted to be rotated, to swing the tool 92 from side to side across the tip of the wheel, by movement of a piston 91 which has rack teeth formed on one side to mesh with the teeth 98 of a spur pinion that is integral with the sleeve 95. The shaft 99 is formed with an arm 99 on its rear end which carries a follower I99. The follower engages the active surface of a cam member I9I which is rectilinearly adjustable in the housing 99 in a direction at right angles to the axis of the shaft 99. This adjustment is effected by rotation of the screw shaft I92 which threads into a nut I93 that is carried by the cam member IIII. This adjustment can be made precisely by means of a graduated dial I94 which is secured to shaft I92 and by means of the index pointer 195 (Fig. 1) which is see cured to the cam member I9I and which reads against the graduated scale I99 that is secured to the housing 99.

The cam member I9I may have an active surface which is in part plane and in part of toric shape, as described in the Wildhaber application above mentioned. As the shaft 99 is revolved, therefore, to swing the dressing tool 92 from one side of the wheel to the other across the tip of the wheel, the shaft 99 will be moved axially to modify the elliptical shape which it would otherwise produce, and form a flattened surface on the tip of the wheel with rounds where the tip surface joins the sides of the wheel. The coil spring I95, which surrounds the shaft 99 and which is interposed between the housing and the which are secured to shafts I29 and I2I, respectively.

During their oscillation, the shafts I29 and I2l may also be moved axially. The axial movements of the shafts are effected through operation of angularly adjustable control members I34 and I35 (Figs. 10, 11, 12 and 14) which are identical with one another. Each of the. control members is formed with spaced trunnions I31 which are mounted in suitable bearings provided The side-dressers and their actuating parts V are mounted in theblock II9 (Figs. 1 and 2) which is mounted on the slide 49 for angular adjustment thereon. This adjustment is effected by rotation of a worm shaft III which-is journaled in the block II2. This block is secured to the slide 49 by means of bolts "3. The worm shaft II I carries a worm II4 that meshes with a worm wheel segment II5 which is secured to or integral with the block H9. The block II9 is secured in adjusted position by means of bolts in the side walls of the housing II9. Between the trunnions I31, each control member is slabbed oif to provide a plane control surface I38. Each of the 'shafts I2 9 and I 2| is provided with an arm I39, and in each of these arms is mounted the ball-shaped follower I49 that engages the plane surface I38 of a control member. The axis of adjustment of the control member passes through the center of the spherical surface of the ball-shaped follower in the middle position of swing of the ball. Each follower I49 is held in engagement with the surface I39 of the corresponding control member by a coil spring I42 which is housed in a recess in the shaft I29 or I2I, as the case may be, and which is interposed between the bottom of this recess and the head of a plunger I43 which is secured in the shaft I29 or I2I.

, Figs. 12 to 15 inclusive illustrate diagrammatically how the control members function in the dressing of the outside and the inside surfaces of the grinding wheel. In Fig. 12, the control member I34 is shown'tilted rearwardly. As the follower I49 travels across the plane face I38 of the control member in the swing of the shaft I29, the point of contact of the follower with the control member will trace an arcuate path I 45 and the shaft I 29 will first be moved rearwardly and then will be moved forwardly again. Thus a convex surface I49 will be formed on the wheel by the outside dressing tool I22.

In Fig. 14, the control member I35 is also shown tilted rearwardly and set at the same angle as the control member I34. As the shaft I 2| is oscillated, the follower I49 will trace the arcuate line of contactil48 onthe plane surface I 38 of the control member and again the dressing tool will first be moved rearwardly and then forwardly again. Since the dressing tool I23 is operating on the inside surface of the wheel, it will thus dress a concave profile shape I41 on the wheel.

In Figs. 12 and 14, the wheel W is shown in section in the plane of the drawings. This is for the purpose of illustration as the wheel, of course, would be perpendicularto the plane of the drawings when the axes I29 and I2I arei the plane of the drawings.

By setting the control members I34 and I 35 toidifferent angles, inside and outside surfaces can be dressed on the wheel having different radii of curvature. When either control member is set to the zero position of its adjustment, there will be no axial movement of the dressing tool a housing I62.

tion shown in Fig. 18 to swing the whole as it swings across the surface being dressed, and the surface dressed will be of approximately straight profile shape.

For adjusting the angular position of each control member, a graduated plate I50 (Fig. 1) is provided. This plate is mounted on the projecting hub portion I5I (Fig. 11) of the control member and is secured thereto by a nut I52. The plate I50 is beveled off at its lower end and provided with graduations to read against an index marked on the side of the housing H0. The plate is secured in any adjusted position by means of a bolt I53 which passes through an arcuate slot I54 in the plate and which threads into the Fig. 18. The operation of these parts is controlled by a manually rotatable valve I60 which is journaled in a sleeve I6I that is mounted in This valve is adapted to be manipulated by a handle I64 which is secured to its projecting stem' portion I65. The housing I62 may be fastened at any convenient point on the grinding machine. e

. The pressure fluid is supplied to the valve I60 fromthe line I10 through the duct I'll. The line I10 also connects with the line 10 that leads to the shuttle valve 62. The motive fluid is exhausted from the valve casing I62 through ducts I12 and I13 which connect withthe duct I14 that leads back to the sump of the machine. The valve is connected to opposite'sidesof the rotary piston 30 (Figs. 3, 4, and 18), which serves to move the dressing mechanism into and out of operative position, by the ducts I82 and I83. The

valve is-connected to one side of the piston I21 (Figs. 2 and 18) which actuates the side-dressers,

by the duct I85. The valve is connected to one side of the piston 91 (Figs. 9 and 18), which actuates the tip dresser, by the duct I 86. The other sides of the pistons I21 and 91 are connected by a. duct I9I. The duct I86communicates with the duct 13 that leads to one side of the shuttle valve 62 (Figs. 6 and 18) The valve I shown is of the same construction as the control valve disclosed in the pending application. of Paul Barker et. al., Serial No.

496,452, filed July 28, 1943. It is provided with the duct I83 is put on exhaust. The duct I86 remains, however, on supply and the duct I 85 on exhaust. When the duct I82 is put on supply, the rotary piston 30 is moved to the full line posidressing mechanism into operative position.

When the dressing mechanism is in operative position, the valve I60 is rotated a step further to put the duct I85 on supply and the duct I86 which is formed. in-the block II 0. The pressure fluid flowing from the duct I 85 into the cylinder- I90 forces the piston I21 downwardly to swing the outside dresser I22 across the outside surface of the grinding wheel from the base to the tip of the wheel and to swing theinside-dresser I23 across the inside surface of the wheel from the tip to the base of the. wheel. As the piston I21 moves downwardly, also, the motive fluid in the lower end of the cylinder I90 is forced out through the duct I9I into the cylinder I92 in which the piston 91,. that actuates the tip-dresser, reciprocates. This causes the piston 91 to be moved to the left (Fig. 18) in this cylinder, forcing the motive fluid out of the left-hand end of this cylinder. There are two ducts I94 and I96 which lead from the left-hand end of this cylinder and which connect with duct I86. The motive fluid flowing from the left-hand end of cylinder I92.

cannot flow through the duct I94 because this duct is closed by a ball check valve. I95; it must flow through the duct I96. The connection of duct I96 with the duct I91 is controlled, however, by an adjustable needle yalve I98. Hence, the movement of piston 91 and of the tip-dresser 92,

.which it operates, is throttled. The setting of needle valve I98 determines the rate of movement of the tip-dresser across the tip and rounds of the wheel and the finish which is dressed on the tip and rounds of the wheel.

At this. time, also, the shuttle valve 62 is held in the position shown in Figs. 6 and 18 by the coil spring 65, for the line 13 which connects with line I86 is like line I86 on exhaust. This allows the pressure fluid to flow from the duct 10 through the ports 66 and 61 (Figs. 6 and 18) of sleeve 64 into the duct 15 that leads to one end of the piston 54. This causes the block 52 (Figs.

5 and 6) to be swung about the axis of the shaft '5I to cause the tip-dresser to be moved into andto be held in operative relation with the grinding wheel. Thus as the tip-dresser 92 moves in one direction during the movement of piston 91 from right to left (Fig. 18), the tip-dresser is held in engagement with the Wheel by pressure of the motive fluid on piston 54,. and the tip and rounds of the wheel are dressed at a rate determined by the setting of needle valve I98.

.The operator now reverses the direction 0 movement of the control valve I60, moving it back one step. This now puts the line I86 on supply and the line I85 on exhaust while maintaining the duct I82 on supply and the duct I83.

5|, to move the tip-dresser away from engage-' ment with the grinding wheel.

At the same time, the pressure fluid flowing through the duct I86 enters the left-hand end of the cylinder I92 through the duct I96 and also through the duct I94, the check valve I95 being forcedopen by the pressure of the motive fluid. This causes'the piston 91 to be moved back to' the right in cylinder I92 and it causes the tip-dresser 92 to be swung back to its starting position. Now as the piston 91 moves back to the right, the motive fluid is forced out of the right hand of the cylinder I92 through the line I9I into the lower end of the cylinder I90. This forces the piston I21 upwardly, rocking the sidedressers back across the outside and inside'surfaces of the grinding wheel to their starting post. tions. Now in the upward movement of pistontip ofthe wheel. The rate of the described mentofthe tip-dressing tool is controlled by e gear without burning.

- is only open when the-duct I85 is on pressure and which at this stage is closed bythe ball check valve I through operation of spring 202 and the pressure of the motive fluid on the ball. The other is through the duct 203,-needle valve 200 and duct 204. The latter connection is operative at this time andthe rate of the return movement of the side-dressers is therefore controlled by. the setting of the needle valve 200. Thus the return strokes of th side-dressers may be controlled to effect finish-dressing of the sides of the wheel. By suitable adjustment of the needle valves I98 and. 200 the forward stroke of the tip-dresser and the return strokes of the side-dressers can be at the same rate, and then the wheel will be dressed to have the same finish on'its sides, tip, and rounds.

When the side and tip-dressers have flnished their return strokes the dressing operation will have been completed. The operator now moves the valve I back to its original position, putting the line I83 on pressure and the line I82 on exhaust, while maintaining the duct I88 on supply and the duct I85 on exhaust. The pressure fluid flowing through the duct I83 swings the piston 30 from the full'line position shown in Fig. 18 to the dotted line position'shown in that figure and thus, the whole dressing mechanism is swung away from operative to inoperative position. The

' dressing cycle has been completed.

the finish which is dressed on the surface.

The principle of operation of the dressing mechanism of the present invention is illustrated diagrammatically in Figs. 16 and 17 in connection with the dressing of a grinding wheel W whose side surfaces are of straight profile shape. In

the first stage of the dressing operation, as already described, the outside-dressing tool I22 moves from the'base to the tip of the wheel while the inside-dressing tool I23 is moving from the tip to the base of the wheel and while the tipdressing tool is moving over the tip of the wheel from outside to inside. In other words. outsidedressing tool I22 swings from a position such as is denoted in dotted lines at I 22a in Fig. 16 to a position such as is shown in full lines at I22b, while the inside-dressing tool I23 is swinging' from a position such as shown in dotted lines at I 23a to a position such as is shown in full lines at I231), and while the tip dressing tool 92 is swinging from dotted line position 92a to full line position 92b. In these movements, the tip of the outsideedressing tool travels in the plane I51, the tip ofthe inside-dressing tool travels in the plane I58 and the tip of tip-dressing tool is travelling in an arc parallel to are I58 and containing the ovesetting of the needle valv I98, and this is adjusted so that a helical'surface will be dressed on the tip of the wheel whose lead'P' is sufliciently fine to obtain the desired smoothness of finish in the bottoms and fillets of the tooth spaces of a h V The throttle valve I98' also controls indirectly theidescribed movementsceding description of the side-dressers for the circuit I--I9I-I86 (Fig. 18) is a substantially closed circuit, The side-dressers I22 and I23 have to travel, however, a greater distance in completing a stroke than the tip-dresser travels, for the height of the sides of .the wheel is greater than the width of the tip of the wheel. The side-dressers have to travel faster than the tip-dresser, therefore, in order that all the dressers may complete their strokes in the time I allowed by the needle-valve I98 for the completion of the stroke of the tip-dresser. The faster rate of travel of the side-dressers is obtained by proper selection of the gearing between the piston I21 and the shafts I20 and I2I (Fig. 2) as compared with the gearing between piston 91 and sleeve 95 (Fig. 9). The faster travel of the side-dressers, however, causes the side-dressing tools to turn helical grooves in the outside I 55 and inside I56 of the wheel whose lead P is-coarser than the lead P of the surface dressed onthe tip the grinding wheel for it is swung away by action of piston 54 (Figs. 6 and 18) on the pivotal block 52 which supports the tip-dresser. The rates of the return movements of the outside and insidedressers is controlled by the setting of needle valve 200 (Fig. 19) This valve is adjusted so that the side dressers may dress surfaces of sufliciently .fine finishon the outside and inside of the wheel to grind the desired finish on the side tooth sur faces of -a gear to be ground. Preferably, the valve 200' is adjusted so that the rate of movement of the inside and outside-dressers on their return strokes will equal the rate of movement of the tip-dresser on its forward stroke and'the lead P of the finished dressed side surfaces of the wheel may'equal the lead P of the surface previously dressed on,th,e tip of the wheel. Thus, the wheel can grind a substantially uniform finish on' the sides, bottoms and fillets of the tooth spaces of a gear. I

The operation of the dressing mechanism of this invention will be understood from the prebut may be briefly summed up here. 1

First, of course, the operator makes the various adjustments required. Thus, the control members I34 and I35 (Figs. 10, 11-, and 12 to 15) are adjusted-in accordancewith the profile shapes desired on the outside and inside surfaces ofthe wheel; the cam IOI (Fig. 9)' is adjusted in accordance withthe shape desired on the tip of the wheel; the block IIO (Fig. 2) is adjusted to position the side-dressing tools so that they" will dress the required pressure angles on the sides of the Wheel; the slide 46 (Fig.2) is positioned so that the wheel are being 52 by adjustment of disc 88 (Figs. and 8) to position the tip-dressing tool radially independently of the radial adjustment of slide", above mentioned, so that the surface dressed by the tipdressing tool may blend with the surfaces dressed by the side dressing tool; and the throttle valves I98 and. 200 (Fig. 18) are adjusted to insure-that surfacesof the proper finish will be dressed on the sides, tip and rounds of, the wheel. The dressing mechanism is then ready for use.

The grinding wheel is swung todressing position by movement of the quill 2I (Fig. 1). To dress the wheel, the operator moves the dressing mechanism into operative position by moving the controlvalve I60 one step. This puts duct I82 (Fig. 18) on supply and duct I83 on exhaust to cause rotary piston 30 to swing support 22 (Fig. 3) about the axis of shaft 24 and move the whole dressing mechanism into operative relation with the grinding wheel. When this has been done, the operator moves control valve I6Il a second step. This puts duct I85 on supply and duct I86 on exhaust. The tip-dresser is moved into operative relation with the tip of the wheel through application of fluid pressure to piston 54 (Figs. 6

and 18) to swing the'block 52 about the axis of til . .with the wheel on its return stroke, the rate of shaft 5| (Figs. 3 and 5) against the resistanc;

of spring 88 (Fig. 7), and the side and tip-dressers are moved across the wheel surfaces through action ofthe pistons I21 and 9'! (Fig. 18). In these movements, the-needle valve I98 is operative to determine the rate of movement of the tip-dresser and the finish dressed on the tip of the wheel. Then, the operator reverses control valve I60 one step to put duct I86 on supply and the direction of movement of the tools and main- .taining the side-dressing tool in engagement with ing the tip-dressing tool from engagement with l the wheel on its return stroke, the rate of the return movement of the side-dressing tool being.

different from the rate of forward movement of said tool.

3. The method of dressing a grinding wheel which comprises moving a side and a tip-.-d'iessing tool across a side and the tip of the wheel, re-

spectively, invone direction, and then reversing the direction of movement of the tools, and maintaining the side-dressing tools in engagement with the wheelduring its return stroke but withholding the tip-dressing tool from engagement return movement of the side-dressing tool being different from the rate of forward movement of duct I85 on exhaust. This produces the return strokes of the side and tip-dressing tools. During their return strokes, the side-dressing tools dress the sides of the wheel to a finish determined by the setting of the needle valve 200, but the tip-dressing tool is out of engagementwith the wheel because the duct 13 (Fig. 18). is on supply and duct 15 is on exhaustand the'spring 80 (Fig. 7) therefore swings block 52 and the tipdresser away from the wheel. The dressingope-ration having beencompleted, the operator now moves control valve I68 back to orignal position to put duct I83 on supply and duct I82 an exhaust to cause rotary piston 30 to swing the whole dressing mechanism about the axis of shaft 24 (Fig. 3) to inoperative position.

While the invention has been described in connection with the dressing of a cup-shaped wheel, it may be employed in dressing other types of' wheels, also, for instance, disc wheels and annular wheels, Further, it-will be understood that .while the invention has been described in connection with a particular embodiment thereof, it is capable of various modifications, and this application is intended to cover any variations, uses, or' adaptations of the invention following, in general, the principles of the invention and includingsuch departures from the present disclosure as home within known or customary practice in the art to which the invention pertains and as a may be applied to the essential features hereinbefore set forth and as fall within the limits of the invention or the scope of the appended claims. Having thus described 'our invention, what we claim is: i 4

1. The method of dressing a grinding wheel whicli'comprises moving a side and a tip-dressing tool "across aside'and the .tip of the wheel, re-

- spectively, in one direction, and then reversing ment of the'dressing mechanism but withholding said tool and being approximately the same as the rate of forward movement of the tip-dressing tool;

4. The method of dressing a grinding wheel which comprises dressing a side of the wheel at one rate of speed and the tip of the wheel at a faster rate,- and redressing the side of the wheel at a faster rate of speed than said first named rate of speed. 5. The method of dressing a grinding wheel I which comprises passing a dressing mechanism in one direction around a side and the tip of the wheel, and then. reversing the direction of move- 6. The method of dressing a cup-shaped grinding wheel which comprises moving 'a side-dressing tool across the outside of the wheel from the base to the tip of the wheel while moving a second side-dressing tool across the inside of the wheel from the tip to the base of the wheel and a tipdressing tool across the tip of the whe 1 from outside to inside thereof, and then rever ing the directions of movements of all three dressing tools to redress the sides of the wheel during the return strokes of the outside and inside-dressing tools, but withholding the tip-dressing tool from en ement with the wheel during its return stroke, the rates of the return movements of the 1 outside and inside tools being faster than the.

rates of their forwardmovements, and the three tools being so positioned that at' substantially mean points in their strokes they lie in. the same radial plane-of the wheel.

7. The method of dressing a cup-'shaped grinding wheel which comprises moving'a side-dressing outside'to the inside thereof,- and then reversing p 2,350, 189 l the directions of movements or all three dressing 7 tools to redress the sides. of the wheel during the return strokes of the outside and inside-dressing tools, but withholding the tip-dressing tool from v engagement with the wheel during its return outside'and inside tools being faster than the rates of their forward movements and approximately the sam as the rate of the forward movement of the tip-dressing tool, and the three tools being so positioned that at approximately mean points in their'strokes they all lie in the same radial plane of the wheel.

8. Mechanism for dressing the side and tip surfaces of a rotary grinding wheel comprising" a support, a dressing tool reciprocably mounted on the supportior dressing one side of the wheel, a second dressing tool reciprocably mounted on the support for dressing the tip of the wheel, means for reciprocating the tools, means for withdrawing the tip-dressing tool from enga ement with the wheel on its return strokes, and means for adjusting the rates of movement in opposite directions of the two tools.

9. Mechanism for dressing'the side and tip surfaces of a rotary grinding wheel comprising a support, a pair of dressing tool mounted on said support and adapted to dress a side and the tip of the wheel, respectively, fluidpressure operated means comprising a cylinder and a piston reciprocable therein for reciprocating each of said dressing tools, said pistons being so connected tooperative engagement with the wheel duringits strokes in both directions, and the tip-dressing 4 tool is in operative engagement with the wheel during its strokes in one direction only and is out of operative position during its strokesin the other direction. I V

10. A dressing mechanism for grinding wheels comprising a supportQa block pivotally mounted on said support, a dressing tool mounted on the block, means for reciprocating the dressing tool, and means for rocking the block about its pivot to cause the tool to engage the wheel to be dressed on movement of the tool in one direction and to be disengaged from the wheel during movement of the tool in the opposite direction.

11. A dressing mechanism for grinding wheels comprising a support, a block pivotallymounted on said support, a dressing tool mounted on the block, fluid-pressure operated means for reciprocating the tool, fluid-pressureoperated means for rocking'the block about its pivot to cause the tool to engage the wheel tobe dressed on movement of the tool in one direction, means for rocking the block about its pivot to'cause the tool to be disengaged from the wheelduring movement of the tool in the opposite direction, and valve means for controlling the timed operation of the two fluid-pressure operated means.

, 12. 'A dressing mechanism for grinding wheels comprising a support, a slide mounted on the sunport for adjustment radially of the wheel axis, a pair of side-dressing tools movably mounted on the slide for dressing opposite sides of the wheel.

' respectively, a tip dr'essing tool movably mounted on the slide for dressing the tip of the wheel, means for actuating the side-dressing tools to swinging the tip-dressing tool back and forth from one side of the wheel to the other to dress the tip of the wheel, said tip-dressing tool being mounted on said slide for adjustment radially of the wheel independently of the radial adjustment of said slide. i

13. A dressing mechanism for grinding wheels comprising a support, a side-dressing tool reciprocably mounted on said support, a carrier re- 10 ciprocably mounted on the support, a tip-dressing tool reciprocably mounted on thecarrier, a v,cy-

linder and a piston reciprocable therein for actuating the side-dressing tool, 'a cylinder and piston reciprocable therein for actuating the tip-dressing the tip-dressing tool to and'irom engagement with the wheel, a reversible shuttle valve controlling the direction of movement of the last named piston, and a single reve se valve controlling the directions of movement of the first two named pistons and of said shuttle valve.

14. A dressing mechanism for grinding wheels comprising a support, a side-dressing tool reciprocably mounted on the support, a carrier reciprocably mounted on the support, and a tipdressing tool reciprocably mounted on the carrier, a cylinder and a piston reciprocable therein for actuating the side-dressing tools, acylinder and a piston reciprocable therein for actuating the tip-dressing tool, said cylinders being connected by a hydraulic circuit which is substantially closed and so constructed that movement of one piston ment with the wheel, a reversible shuttle valve controlling. the direction of movement of the last named piston, a single reverse valve controlling the directions of movement of the first two named pistons and of said shuttle valveyand separately directions to move the dressing tools into and out of operative relation with the wheel, fluidpressure operated means for actuating each of the dressing tools, when in operative position, and a 0 single control'valve for controlling the operations o of all fluid-pressure operated means.

16. In a grinding machine, a support, a grind- I ing wheel rotatably mounted on the support, a

dresser carrier movably mounted on the support;

a block movably mounted on the carrier, 9. sidedressing tool movably mounted on the carrier, a

tip-dressing tool movably mounted onsaid block,

means for moving the carrier in opposite direc- 7 tions to move the dressing tools into and out of operative relation with the wheel, means for reciprocating the tools, when in operative position, to effect dressing of the wheel, and means for moving the block on the carrier to move the tipdress opposite sides-of the wheel, and means for (5 dressing to l int and t of, engagement with ated means for moving the carrier in opposite direction while the wheel independently of the movement or the carrier. I 17. In agrinding-machine, a support; a grinding wheel rotatably mounted on the support, a dresser carrier movably mounted on the support. a block movably mounted on the carrier, a side- ,dressing tool movably' mounted on the carrier, 9. tip-dressing tool movably mounted on the block, fluid-pressure operated means for moving the carrier in opposite directions onthesupport to move the dressing tools into and out'of operative ment in opposite directions, respectively, of the relation with the wheel, fluid-pressure operated means for reciprocating the tools', when in operative position, to effect dressing of the wheel, fluid- I pressure operated means for moving the block on the carrier to move the tip-dressing tool into and out of engagement with the wheel, and a single control valvecontrolling all said fluid-pressure operated means.

18. In a grinding machine, a support, a grinding wheel rotatably mountedv on the-support, a

asecnse from the wheel but the side-dressing tool is in engagement with the wheel, and then to move the carrier to move both tools out of operative position, and separate, independently adjustable throttle valves for controlling'the rates of movetwo pistonswhich actuate the dressing tools.

19. A dressing mechanism for grinding wheels comprising a support, a shaft mounted in said support for rotary and axial movement about an axis perpendicular top, side of the wheel, an arm secured to said shaft at one nd thereof, a dressing tool carried by the arm nd' adapted to dress a side of the grindingwheel, a second arm secured to the opposite end of said shaft, 9. control memher having a plane control surface mounted on dresser carrier rotatably mounted on the support,

a block movably-mounted on the carrier, a sidedressingtool movably mounted on the carrier, a

the movement of the carrier, and a singlecontrol valve controlling all of said fluid-pressure operated means and operable first to move the carrier' int operative position, thentomove the dressing tools'in one direction across the wheel then to move the dressing tools the ti in the opposite with the wheel, a pair of cylinders and a pair said support for angular adjustment about an axis perpendicular to the axis of the shaft to vary the inclination of its control surface to the axis of the shaft, a follower carried by said second arm and adapted to engage said control member, and means for-oscillating the shaft.

20. A dressing mechanism comprising a sup- 'port, a, shaft mounted on said support for rotary and axial movement about an axis perpendicular to a side of the'wheel, an arm secured to said shaft at one end thereof, a dressing toolicarried dressing tool is disengaged by said arm and adapted to dress a side of the grinding wheel, a second arm secured to the opposite end of the shaft, a control member having a plane control surface mounted on said support for angular adjustment about an axis perpendicular to the axis of said shaft to vary the inclination of said control surface to the axis of the shaft, a ball follower carried by said second arm and adapted to engage said control member, the

center of said ball "ment of the control member, and means for oscillying on the axis of adjustlating the shaft.

- ERNEST WILDHABER.

ARTHUR L. STEWART. ARTHUR FUMIA. 

